Vince is the vegan-politico, as a vegan would not eat turkey, or drink a shake (it contains dairy products), Sally rhymes with tally, which can mean the same as count, so Sally is the doctor. This leaves Crazypuzz as the crypto-maniac (unless you found a word that can mean 'count' and rhymes with Crazypuzz :-). The shirts they were wearing was a complete red herring, as it was not supposed to be helpful in solving the puzzle at all.